Building tiny RC blimps has become very accessible with the ultra micro RC-gear available today at affordable prices. Plantraco’s awesome Nanoblimp, a RTF featherweight dog fighting champion, illustrates that. It is just new on the market and if I see it right it must be under 6g, allowing for the use of a 9” balloon. It follows the line set with Plantraco’s earlier Microblimp, with its gondola at 10-12g. The Ballooncraft micro blimp on the other hand has been on the market for quite a while, but using a 17” balloon (putting it near 30g without payload), that’s has become a heavyweight in the Microblimp League.
Anyway it is always more fun making one yourself. For me the trigger was the market appearance of the wonderful tiny DelTang DSM2 receivers, with a weight of 0.23g or 0.65g including connectors. And hacking sub micro servos makes the rest of the build quite simple.You only need to be willing to work with the tiny gear, keeping the total weight near or under 10 g (situating it between Plantraco’s Microblimp and Nanoblimp). Check it out in this video:
I have been building indoor RC blimps for about 12 years now, and dismantling servos has often been the main source for reversible motor controllers and small motors, mainly for the for the tail rotors. For this project the complete three axis propulsion is based on hacked servos.
The servo circuits do not give a perfect proportional control. Actually the concept makes use of the imperfect on/off working of these circuits. In a servo, gets power as soon as the potentiometer is not in the desired position corresponding to the transmitter’s stick position (for some more "theory of operation" on servos check here). But the analogue circuits in ordinary servos do not give full power when the deviation is small. The ones in digital servos do, so these are not suitable for this hack.
As people building tiny RC stuff know, at this scale wiring and connectors become important in the weight. But for this Ible I kept things basic,holding on to the connectors and avoiding soldering. In general soldering is not difficult, but at this scale it does need some experience and the right gear. Obviously this means there is some room for further weight loss, and in step 7 I list some tips for more experienced builders.
You can fly your blimp around in at home and if you have two you can go for a "Plantraco style dogfight" attaching a short pin on the front of each balloon.
Or you can go for a payload version and add a miniature camera. With a large enough balloon a wireless camera is possible, but I kept to a miniature recording camera giving a total weight for camera + propulsion of about 20 g (see last step). Here is a video of the camera version:
If you like this Ible, please don’t forget to give it your vote. Many thanks for your attention!
Step 1: Required RC gear
An ultra micro receiver: I used DelTang Rx33. In any case, chose one below 2g and working on a single LiPo cell (commonly referred to as 1s). Actually many receivers do work on 1s, even if not documented as such. Make sure your servos’ and receiver’s connectors are compatible, or you’re in for some soldering after all. Both the DelTang DSM2 receivers and the blue arrow servos come in a number of connector versions. Specialised online shops like Micron Radio Control. Plantraco or Aether Sciences RC can help in this.
Obviously you will need a compatible transmitter. The simplest one with 3 or more channels will suffice.
A 70 to 140 mAh 1s lipo battery (and a suitable charger): The smallest batteries (around 2.5 g for a 70 mAh) are needed to keep the weight under 10g. A larger battery obviously gives you a longer flight time, but even as flight time is very dependent on flying style, it is easily half an hour with a 125 mAh (weighing 3.5g). A smaller battery will still easily last 15 min or more and it will make a latex balloon last longer (making room for more ballast to compensate for lost helium).
Leads to connect your battery to your receiver (again the specialist RC shop can help in this).
Three small propellers: I used the Plantraco 32 mm “butterfly” propellers. These are some amazing high performance tiny propellers that fit a 0.7mm shaft. The "AES-H34 - Hélice Micro" from Aether Sciences RC looks very suitable too.
A 1mm carbon rod, about 30 cm long
A piece of Depron, about 10 cm by 10 cm, 1mm thick (if not available 3mm thick Depron can be used too).
Some putty as ballast.
Finally, you will need some cellophane tape (sellotape, scotch tape), a pair of small pliers, a couple of small elastic band, superglue and a pair of scissors. A scale, accurate to 0.1g or better, comes in handy. Soldering is optional.
The balloon is described in the next step, the camera and related stuf is described in the last step.
If you already have a transmitter and a charger for the flight battery, the materials needed will cost up to 80 EUR. If you source your servos and propellers cheap you can bring this down significantly. If on top of that you go for a slightly larger version with a 2g receiver, you can you bring it down to under 30 EUR.
A suitable transmitter and charger shouldn’t set you back more than 50 EUR. That is slightly more than the complete Plantraco NanoBlimp, but then we are talking of a DSM2 system, with far more than 4 frequencies available.